North Korea hacked blueprints of warships and submarines in a heist last year of classified documents from a South Korean shipbuilder, Dong-A Ilbo newspaper reported, citing opposition party lawmaker Kyeong Dae-soo.

About 60 classified military documents were among the 40,000 hacked from South Korea’s Daewoo Shipbuilding and Marine Engineering Co. in April 2016, Bloomberg reported. They included information on construction technology, blueprints, weapons systems, and evaluations of the ships and submarines.

South Korea’s Aegis-equipped ships and submarines are key to plans for a preemptive strike against North Korea should it send a submarine equipped with ballistic missiles to target key facilities in the South. Kyeong told the newspaper that he received a briefing on the hack from South Korea’s Defense Ministry, which inspected the shipbuilder for six months.

Earlier this month, a separate South Korean lawmaker said that North Korean hackers stole military plans developed by the U.S. and South Korea last year that included a highly classified “decapitation strike” against leader Kim Jong Un.

Kim’s regime has been developing cyber capabilities as trade sanctions and a debilitated domestic economy make it difficult to invest in conventional military capabilities. It has been accused of hacking everything from Sony Corp. to Bangladesh’s central bank to bitcoin and other cryptocurrencies.

North Korea on Monday denied an accusation that it hacked the U.K.’s National Health Service.

“We made it very clear that the DPRK had no connection at all with acts of cybercrime,” the official Korean Central News Agency reported, citing a spokesperson from the Korea-Europe Association who used the country’s formal name.

North Korea hacked blueprints of warships and submarines in a heist last year of classified documents from a South Korean shipbuilder, Dong-A Ilbo newspaper reported, citing opposition party lawmaker Kyeong Dae-soo.